Hi guys, I've got an LT-80 that I've just stripped and found that the piston is badly scored and so is the barrel. I had a new piston and rings on it about this time last year so has confused my why this has happened again?

My first thought was that it hasn't been getting 2-stroke oil. I've turned the crank and found that the pump seems to be working and oil has definately been going from the tank.

This leads me to think that the crank bearing needs replacing. I've taken the piston off and if I wobble the con rod, there is a lot of lateral play in the bottom bearing.

I'm thinking there is some piston slap going on here. Can anyone shed any light on this? (i.e Is LT-80 reading this and going to educate me!!! LOL!!!!)

I'm in the UK and quite often come on here for advice and tips.

Also after the valve clearances for a Z250.

Cheers in advance guys.

 

There is always some play in it. Altho, too much play would indicate a bad brg. Can you pull it (the rod) up and down and feel any play?
A bad rod brg shouldn't have caused the piston to go bad tho.
I'd get rid of the injector and run pre-mix.
Did it idle OK before the piston went out? ie: possible seal leak leaning the fuel mix.
I'll think on this.

 

I've checked the con rod and there is quite a bit of left to right play when you wiggle it but not really any up and down play if that makes sense?

I can't remember if it was idling OK before it went kapput? Can you just explain what happens the seal issue leaning the mixture? i.e what seals?

At the mo I'm inclined just to replace the piston and rings and cylinder and gasket and run pre-mix as you suggested. What ratio is best? I've always got 25:1 and 50:1 pre-mixed for strimmer and Chain saws etc....

Cheers for help. Always appreciated.

 

Guessing 32.1

 

yup..32:1

 

Brilliant guys, cheers.

So I've ordered a stock piston, rings, barrel and gaskets. Will fit these and then put the bike back together. I'm gonna run 32:1 pre-mix as you have suggested but what should I do with the original injector and oil circuitry?

Shall I just empty the oil tank and leave everything as and just run it pre-mix?

Thanks.

 

But better yet just take the injector pump off and replace it with an injector cover. they sale em and they are pretty cheap. then you wont have the drag of the engine running the pump ad robbing power. just take all that stuff off (tank, Lines, and pump).